Modern mining techniques make extensive use of endless belts to carry mined material from one location to another. For example, continuous belts may be used to carry mined material out of a mine and deposit it external to the mine. Endless belts may also be employed for carrying materials between processes. These belts can be extremely long and can move the material at high linear speeds. At the end of the belt, or rather where the belt begins its return journey, the belt passes around a wheel or pulley and begins the return journey. At that location, the materials on the belt are deposited. However, it is common for some residual material to adhere to the belt.
To reduce dust problems, particularly in coal mining, the load on the belt is sprayed with water. While this suppresses the dust, it increases the amount of material that adheres to the belt when the load is dumped. This material can transfer to pulleys, rollers, idlers, and bearings and build up. This build up of material causes excessive wear at a minimum and can cause seizing in bearings and may lead to fires, a catastrophic result. Belt scrapers are employed to remove this material from the belts to prevent the transfer to other elements of the conveying system, thereby preventing damage to those elements.
Scrapers are positioned to contact the belt on the terminating wheel or on the return run of the belt to remove this residual material. The dynamic nature of the environment and the abrasive nature of the materials being carried by the endless belt require belt scrapers that are durable and that can be maintained in contact with the belt with consistent pressure. The belt scrapers are expendable elements of the system and any economy that can be achieved with the belt scrapers is an improvement in the economic efficiency of the system. It is therefore highly desirable to have belt scrapers that are durable, that can be used over an extended period of time, and that can be economically manufactured.
Because of the width of the belt, the belt scraping elements that actually contact the belts are frequently divided into subsections so that they are lighter than if they were constructed to span the width of the belt. Although this leads to lighter elements, it requires multiple sections of scraper blades to be installed and this causes an increase in installation time and complications. However, while a single scraper blade that spans the width of the belt avoids the problems of multiple segments, it presents a single heavier unit. In particular, reversible scraper blades having two scraping edges will be heavier still. Since the components of a belt scraping apparatus must be carried and manipulated for installation, it is desirable to have scraping edges that span the width of the belt while limiting the weight that must be carried by personnel.